TDA8137 Datasheet, PDF (4/5 Pages) STMicroelectronics – DUAL 5.1V REGULATOR WITH DISABLE AND RESET

TDA8137
CIRCUIT DESCRIPTION
The TDA8137 is a dual voltage regulator with Reset
and Disable.
The two regulation parts are supplied from one
voltage reference circuit trimmed by zener zap
during EWS test. Since the supply voltage of this
last is connected at Pin 1 (VIN1), the regulator 2 will
not work if the Pin 1 is not supplied.
The outputs stages have been realized in dar-
lington configuration with a drop typical of 1.2V.
The disable circuit, switches off the output 2 if a
voltage lower than 0.8V is applied at pin 3.
TYPICAL APPLICATION
The Reset circuit checks the voltage at the output
1. If this one goes below VOUT - 0.25V (4.85V Typ.),
the comparator "a" (see Figure 1) discharges rap-
idly the capacitor Ce and the reset output goes at
once low. When the voltage at the OUT 1 rises
above VOUT -0.2V (4.9V Typ.), the voltage VCe
increases linearly to 2.5V corresponding to a delay
td
following
the
low
:
t_d
=
Ce ⋅ 2.5V
10µA
(see
figure
2),
then the reset output goes high again. To avoid
glitches in the reset output, the second comparator
"b" has a large hysteresis (1.9V).
V_IN1
C1
1
7
TDA8137
2
6
Ce
4
5
3
C2
RESET _DISABLE
C1
.
.
C3 = 10µF
V _O1
V _O2
C3
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